Electrolytes for wide-temperature range lithium ion batteries

Abstract

Electrolytes for lithium ion batteries operable over a wide temperature range are disclosed. A lithium ion battery including a disclosed electrolyte may be operable over a temperature range of from −50 ° C. to 60 ° C. The electrolytes include a lithium salt, a non-aqueous carbonate-based solvent, a cesium salt and/or rubidium salt as a first additive, and two or more additional additives.

We claim: 
     
         1 . An electrolyte, comprising:
 2-2 M lithium salt;   a nonaqueous carbonate-based solvent comprising one or more carbonate compounds;   01-0.2 M of a first additive, wherein the first additive comprises a cesium salt, a rubidium salt, or a combination thereof;   01-5 wt % of a second additive, wherein the second additive comprises a fluorinated cyclic carbonate compound, an unsaturated cyclic carbonate compound, or a combination thereof; and   01-5 wt % of a third additive, wherein the third additive comprises an organic phosphite compound, an amine, a sultone, an imide, or a combination thereof,   wherein the second additive is not the same as the one or more carbonate compounds of the nonaqueous carbonate-based solvent, and   wherein if the lithium salt comprises LiFSI, then the third additive does not comprise LiFSI.   
     
     
         2 . The electrolyte of  claim 1 , comprising:
 2-2 M lithium salt;   01-0.2 M of the first additive;   1-2 wt % of the second additive; and   0.1-2 wt % of the third additive.   
     
     
         3 . The electrolyte of  claim 1 , wherein:
 the lithium salt comprises lithium hexafluorophosphate (LiPF 6  ); and   the first additive is cesium hexafluorophosphate (CsPF 6 ).   
     
     
         4 . The electrolyte of  claim 1 , wherein the nonaqueous carbonate-based solvent comprises ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), di(2,2,2-trifluoroethyl) carbonate (DTFEC), methyl 2,2,2-trifluoroethyl carbonate (MTFEC), or a combination thereof. 
     
     
         5 . The electrolyte of  claim 4 , wherein the nonaqueous carbonate-based solvent consists essentially of EC, PC, and EMC. 
     
     
         6 . The electrolyte of  claim 4 , wherein the nonaqueous carbonate-based solvent consists essentially of EC, PC, EMC, DEC, and DMC. 
     
     
         7 . The electrolyte of  claim 1 , wherein the second additive comprises fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 4-methylene ethylene carbonate (MEC), 4,5-dimethylene ethylene carbonate (DMEC), or a combination thereof. 
     
     
         8 . The electrolyte of  claim 1 , wherein the third additive comprises tris(trimethylsilyl)phosphite (TTMSPi), N-(trimethylsilyl)diethylamine (TMSDEA), 1,3-propane sultone (PS), lithium bis(fluorosulfonyl)imide (LiFSI), or a combination thereof. 
     
     
         9 . The electrolyte of  claim 1 , wherein the second additive comprises FEC or VC and the third additive comprises TTMSPi. 
     
     
         10 . The electrolyte of  claim 9 , wherein the third additive further comprises PS, LiFSI, or a combination thereof. 
     
     
         11 . The electrolyte of  claim 1 , comprising:
 1 M lithium salt provided by 0.7-1 M LiPF 6  and 0-0.3 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), LiBF 4 , or a combination thereof;   EC, PC, and EMC;   05 M CsPF 6 ;   25-0.5 wt % VC, 0.25-0.5 wt % FEC, or 0.25-0.5 wt % FEC+VC; and   0.5 wt % TTMSPi.   
     
     
         12 . The electrolyte of  claim 11 , further comprising 0.25-1 wt % PS, 0.25-1 wt % LiFSI, or a combination thereof. 
     
     
         13 . The electrolyte of  claim 1 , consisting essentially of:
 LiPF 6,  or LiPF 6  in combination with LiTFSI, LiBF 4 , or LiTFSI and LiBF 4 ;   EC, PC, and EMC;   CsPF 6 ;   FEC, VC, or FEC and VC;   TTMSPi;   0-5 wt % PS; and   0-5 wt % LiFSI.   
     
     
         14 . The electrolyte of  claim 1 , consisting essentially of:
 (i) 1 M lithium salt provided by LiPF 6  or (ii) 0.7-0.8 M LiPF 6  and 0.2-0.3 M LiTFSI, LiBF 4 , or LiTFSI and LiBF 4 ;   EC:PC:EMC in a weight ratio of 1:1:8;   0.05 M CsPF 6 ;   25-0.5 wt % FEC or 0.25-0.5 wt % VC;   5 wt % TTMSPi;   0-0.5 wt % PS; and   0-1.5 wt % LiFSI.   
     
     
         15 . The electrolyte of  claim 1 , consisting essentially of:
 (i) 0.8 M LiPF 6  and 0.2 M LiTFSI, or (ii) 0.7 M LiPF 6  and 0.3 M LiBF 4 ;   EC:PC:EMC in a weight ratio of 1:1:8;   0.05 M CsPF 6 ;   0.25 wt % VC;   0.5 wt % TTMSPi;   0.5 wt % PS; and   0.25 wt % LiFSI.   
     
     
         16 . The electrolyte of  claim 1 , consisting essentially of:
 1 M LiPF 6 ;   EC:PC:EMC in a weight ratio of 1:1:8 or EC:PC:EMC:DEC:DMC in a weight ratio of 1:1:4:2:2;   0.05 M CsPF 6 ;   0.25 wt % FEC;   0.5 wt % TTMSPi;   0.5 wt % PS; and   0.25 wt % LiFSI.   
     
     
         17 . A lithium ion battery system, comprising:
 an anode;   a cathode; and   an electrolyte according to  claim 1 ,   wherein the battery is operable over a temperature range of from −50° C. to 60° C.   
     
     
         18 . The battery system of  claim 17 , wherein:
 the anode is a carbon-based anode; and   the cathode comprises a lithium transition metal oxide or a lithium transition metal phosphate.   
     
     
         19 . The battery system of  claim 17 , wherein:
 the anode comprises graphite;   the cathode comprises a lithium transition metal oxide; and   the electrolyte comprises
 5-1.5 M lithium salt, 
 0.025-0.1 M of the first additive, 
 0.25-1 wt % of the second additive, and 
 0.25-2 wt % of the third additive. 
   
     
     
         20 . The battery system of  claim 17 , wherein the electrolyte consists essentially of:
 1 M lithium salt provided by LiPF 6  or LiPF 6  in combination with LiTFSI, LiBF 4 , or LiTFSI and LiBF 4 ;   EC, PC, and EMC in a weight ratio of 1:1:8 or EC:PC:EMC:DEC:DMC in a weight ratio of 1:1:4:2:2;   0.5 M CsPF 6 ;   0.25-0.5 wt % VC, 0.25-0.5 wt % FEC, or 0.25-0.5 wt % FEC+VC;   0.5 wt % TTMSPi;   0-0.5 wt % PS; and   0-1 wt % LiFSI.